Add instruction on how to build API reference
Add instruction on how to build API reference

Change-Id: I1ba49f2741531e873fae98ae1b1c933c60896b14
Reviewed-on: http://review.couchbase.org/71605
Reviewed-by: Sergey Avseyev <87f6d5e4fd3644c3c20800cde7fd3ad1569370b3@gmail.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

couchbase/php-couchbase,couchbaselabs/php-couchbase,couchbase/php-couchbase,couchbase/php-couchbase,couchbase/php-couchbase,couchbaselabs/php-couchbase,couchbaselabs/php-couchbase,couchbaselabs/php-couchbase